Background: In exploratory learning, students first explore a new topic with an activity and then receive instruction. This inversion of the traditional tell-then-practice order typically benefits conceptual knowledge and transfer, but not always. Aims: The current work examines the impact of including contrasting cases in an exploration activity, which can enhance student perception of novel problem features. Samples: Undergraduate physics students (Experiment 1, N = 129; Experiment 2, N = 92) participated as part of their regular classroom instruction. Methods: Students completed an activity either before or after instruction (explore-first or instruct-first conditions). In Experiment 1, the activity included contrasting cases; in Experiment 2, the activity instead included a rich dataset. Students completed a post-test assessing procedural knowledge, conceptual knowledge and transfer. Results: In Experiment 1, students in the explore-first condition demonstrated similar procedural knowledge, higher conceptual knowledge and higher transfer than students in the instruct-first condition. In Experiment 2, there were no significant differences in learning outcomes between explore-first and instruct-first conditions. In both experiments, students in the explore-first and instruct-first conditions reported similar cognitive load and interest and enjoyment after the activity. Conclusions: Contrasting cases may be important when designing exploratory learning activities, helping to improve both conceptual understanding and transfer to new topics.